1. Field of the Invention
The present invention relates to a waterproof structure, which can be applied to an engine start switch, and a switch device.
2. Description of the Related Art
An in-vehicle switch device such as an engine start switch, which illuminates an operation surface of an operation button by the pressing operation of the operation button, is known (for example, see Japanese Unexamined Patent Application Publication No. 2011-124030). An operation button is slidably received in a cylindrical case of the switch device so that an operation surface is exposed to the outside, and a substrate provided with a light-emitting element such as an LED is received on the inner side of the operation button. A rubber contact is mounted on the substrate. When the rubber contact is pressed against the operation button, the light-emitting element emits light. In this way, the operation surface of the operation button is illuminated from the inside of the case by the light-emitting element mounted on the substrate.
Incidentally, the switch device disclosed in Japanese Unexamined Patent Application Publication No. 2011-124030 is provided with a support member that supports the substrate in the case. The support member has an outer surface that faces the inner surface of the case with a small gap interposed therebetween. For this reason, when water droplets adhere to the back side of the switch device due to dew condensation or the like, there is a concern that the water droplets infiltrate into the case through a gap between the inner surface of the case and the outer surface of the support member due to capillary phenomenon and cause the corrosion of electronic components mounted on the substrate.
Meanwhile, a structure, which prevents the infiltration of water droplets into the case by making temperature inside the case be close to temperature outside the case to suppress the negative pressure in the case, is also considered, but there is a problem in that the number of parts or man-hour is increased and the size of a device or the manufacturing cost is increased. Further, there are concerns that the internal pressure is increased due to the rise of internal temperature caused by a heat-generating component present in the case and abnormality occurs.